Awnings of the roll-up type are well-known in the recreational vehicle field for providing shade and cover from inclement weather, and also for providing additional living space adjacent to the vehicle.
Roll-up awnings are also used in a variety of other settings where temporary cover is required. For example, and without limitation, roll-up awnings are used on hotel and shop fronts, and on trailer homes. One edge of the awning is fixed to the vehicle or building and, in the stored position, the other end is wrapped around a spring-loaded roller tube. The awning can be mounted to the roller tube by means of slideways extending longitudinally within the exterior surface of the roller tube. The roller tube can be pivotably supported by arms extending from the vehicle or building, and can be further supported from the ground by poles, or from the vehicle or building by outriggers. The awning is deployed by unrolling the awning from the roller tube against spring resistance, and supporting and locking the unrolled awning in place. Subsequent stowing of the awning onto the roller tube is facilitated by the aforementioned spring-loading.
In the deployed position, the roller tube must support its own weight, the weight of the awning, and the weight of other attachments such as screens or valances. In addition, the roller tube must resist wind forces acting on the awning, and support any additional weight due to precipitation accumulating on the awning. Because the area of awning and the length of the roller tube can be large (roller tubes of 21 feet or more in length are commonly used), the roller tube must be strongly constructed to minimize bowing or bending in use. A common failure mode of roller tubes is for initial bowing to facilitate further accumulation of precipitation on the awning, leading to complete structural failure of the roller tube.
In the past, a long roller tube would sag between its end supports. To mitigate this problem, additional supports can be used; the roller tube can be constructed from strong materials such as extruded aluminum or steel; and/or stiffening inserts can be positioned within the roller tube.
Examples of each of these approaches can be found, for example, in the following patents. U.S. Pat. No. 4,258,778 discloses a roller tube formed from sheet metal, with optional reinforcement provided by inserts or foamed plastic placed within the roller tube; U.S. Pat. No. 4,508,126 discloses partial length stiffeners for a roller tube; U.S. Pat. No. 5,351,736 discloses a roll-formed roller tube with strengthening ridges formed in its surface; and U.S. Pat. No. 6,598,612 B1 discloses an awning having a mansard shape for minimizing the accumulation of precipitation on the awning and aerodynamically reducing the effect of wind on the awning.
Each of the aforementioned approaches suffers from one or more of the following drawbacks: roll-forming long roller tubes from a sheet metal such as steel has proved to be technically difficult; the stiffeners have a low stiffness to weight ratio; the stiffeners have elaborate shapes that are expensive to make; the stiffeners comprise welds or joints that are expensive to form and which may accumulate stresses and fail in use; or additional supports for the awning are required, which may be cumbersome or obstructive.
Notwithstanding the existence of a variety of awning roller tube strengthening devices in the prior art, there is a continuing need for improved means for reinforcing awning roller tubes that can be simply and inexpensively manufactured from commonly available, light weight materials without the need for welding or jointing, and which minimize the risk of roller tube bending or failure from precipitation or wind. The present invention substantially fulfills these needs. All this and more will become apparent to one of ordinary skill upon reading the disclosure, drawings, and claims appended hereto.